Vertical pass-through for a data storage library

ABSTRACT

Embodiments include systems and methods for providing throughput increase and/or physical expansion of a data storage library. Some embodiments include multiple robotic assemblies, each having its own hand assembly, which are electrically and mechanically integrated for concurrent use in a single storage library environment for increased throughput. Other embodiments include an active vertical pass-through assembly that operates to ferry cartridges from one storage library environment to another, vertically adjacent storage library environment. Some such embodiments use existing robotic mechanisms of the libraries to exploit a shared slot through which vertical pass-through functionality can be realized. Other embodiments include an active horizontal pass-through assembly that operates to ferry cartridges from one storage library environment to another, horizontally adjacent storage library environment. Some such embodiments include a separate robotic mechanism that couples with each library and actively passes a cartridge among them and is adjustable to varying spans between the libraries.

FIELD

Embodiments relate generally to data storage systems, and, moreparticularly, to scaling storage libraries by using multiple roboticassemblies and/or pass-throughs.

BACKGROUND

Storage library systems are often used by enterprises and the like toefficiently store and retrieve data from storage media. In the case ofsome storage libraries, the media are data cartridges (e.g., tapecartridges) that are typically stored and indexed within a set ofmagazines. When particular data is requested, a specialized roboticmechanism finds the appropriate cartridge, removes the cartridge fromits magazine, and carries the cartridge to a drive that is designed toreceive the cartridge and read its contents. Some storage libraries havemultiple drives that can operate concurrently to perform input/output(JO) operations on multiple cartridges.

One limitation of some such storage library systems is that thethroughput of the system (e.g., how quickly data can be accessed) is atleast partly dependent on physical constraints relating to moving therobot, picking and placing cartridges, etc. For example, expanding thesize of the library can effectively increase the distances traversed bythe robot when performing pick and place operations, and the like, whichcan thereby increase access times and reduce throughput. Anotherlimitation of some such storage library systems is that a fixed numberof cartridges fit in the library. For example, if a library is intendedto fit in half of a standard equipment rack, that overall footprint candrive the space available for cartridges, magazines, etc. To use morecartridges, customers typically purchase an additional library thatoperates independent of the other library.

BRIEF SUMMARY

Among other things, systems and methods are described for providingthroughput increase and/or physical expansion of a data storage library.Embodiments operate in context of a data storage library having a numberof media cartridges physically located within slots of one or moremagazines. A robot with a hand assembly uses a gripper mechanism toretrieve and ferry the cartridges between the magazines and one or moremedia drives. Some embodiments include multiple robotic assemblies, eachhaving its own hand assembly and gripper mechanism, which areelectrically and mechanically integrated in a manner that allows forconcurrent use of the two robots in a single storage library environmentfor increased throughput. For example, as one robotic assembly locates afirst cartridge and ferries it to a designated media drive, anotherrobotic assembly locates a second cartridge and ferries it to a secondmedia drive.

Other embodiments include an active vertical pass-through assembly thatoperates to ferry cartridges from one storage library environment toanother, vertically adjacent storage library environment. For example, afirst storage library installed in a top half of an equipment rack canbe coupled with a second storage library installed in a bottom half ofthe equipment rack via the vertical pass-through, so that cartridges canbe passed between the two libraries. Implementations of the verticalpass-through assembly use the robotic assembly of one library toactively pass cartridges to a slot in the other library, where they canbe picked up by the robotic assembly of the other library.

Other embodiments include an active horizontal pass-through assemblythat operates to ferry cartridges from one storage library environmentto another, horizontally adjacent storage library environment. Forexample, a first storage library installed in a first equipment rack canbe coupled with a second storage library installed in a second equipmentrack via the horizontal pass-through. The robotic assembly of onelibrary can place a cartridge in a slot of the horizontal pass-through,and the horizontal pass-through can actively ferry the cartridge to theother library, where the cartridge can be picked up by the roboticassembly of the other library. Implementations of the horizontalpass-through assembly are expandable to fit multiple horizontalseparations between libraries.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is described in conjunction with the appendedfigures:

FIG. 1 shows a block diagram of an illustrative rack-mounted storagelibrary, to provide a context for various embodiments;

FIGS. 2A and 2B show rear and front views, respectively, of anillustrative base module, according to various embodiments;

FIGS. 3A and 3B show rear and front views, respectively, of anillustrative expansion module, according to various embodiments;

FIG. 4A shows a view looking down on the underside of an illustrativerobot CRU (customer replaceable unit), according to various embodiments;

FIG. 4B shows another view looking up at the underside of anillustrative robot CRU with the Z-platform assembly partially lowered,according to various embodiments;

FIG. 5 shows a partial illustrative multi-robot CRU that has twoZ-platform assemblies, each partially lowered, according to variousembodiments;

FIGS. 6A and 6B show views of an illustrative storage libraryenvironment having multiple robotic assemblies, according to variousembodiments;

FIG. 7 shows an exploded view of an illustrative configuration of apartial Z-drive assembly for use with multiple robotic assemblies,according to various embodiments;

FIG. 8 shows an upper physical library environment and a lower physicallibrary environment configured for vertical pass-through functionality,according to various embodiments;

FIGS. 9A and 9B show vertical pass-through functionality in context of astacked storage library environment, according to various embodiments;

FIGS. 10A and 10B show storage library environments, each having storagelibraries on respective, horizontally adjacent equipment racks;

FIG. 11 shows a partial library environment having an illustrativehorizontal pass-through assembly between two, horizontally adjacentstorage libraries spaced apart by a horizontal span;

FIG. 12A shows a simplified block diagram of a horizontal pass-throughassembly, according to various embodiments;

FIG. 12B shows another view of the horizontal pass-through assembly ofFIG. 12A, to illustrate certain features of some implementations;

FIG. 13 shows a first view of an illustrative implementation of ahorizontal pass-through assembly, according to various embodiments;

FIG. 14 shows a second view of the illustrative implementation of ahorizontal pass-through assembly of FIG. 13, according to variousembodiments;

FIGS. 15A and 15B show views of a horizontal pass-through assemblyinstalled in an illustrative library environment; and

FIG. 16 shows an installation that includes a dedicated horizontal passthrough module that can be added to each storage library.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a second label thatdistinguishes among the similar components. If only the first referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same first reference labelirrespective of the second reference label.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the present invention. However, onehaving ordinary skill in the art should recognize that the invention maybe practiced without these specific details. In some instances,circuits, structures, and techniques have not been shown in detail toavoid obscuring the present invention.

For the sake of context, FIG. 1 shows a rack-mounted storage library 100for use with various embodiments. The storage library 100 includes abase module 110 and one or more expansion modules 120, configured to bemounted in an equipment rack 130 (only the mounting rails of theequipment rack 130 are shown for simplicity). The base module 110 andexpansion modules 120 provide physical storage for multiple storagemedia cartridges (e.g., tape cartridges) in magazines 140. Embodimentsalso include one or more media drives (e.g., tape drives), controllers,power supplies, indicators, communications subsystems, and/or otherfunctions. As will be discussed more fully below, the storage library100 also includes a robotic mechanism for finding and ferrying storagemedia cartridges between locations within the storage library 100 (e.g.,magazines 140 and drives).

According to an illustrative embodiment, the storage library 100 is asmall, rack-mounted, automated tape library. The base module 110 is “3RU” high (three standard rack units, or approximately 5.25-inch high)and includes one robotic mechanism. Up to nine additional, “2 RU” high(approximately 3.5-inch high) expansion modules 120 can be added toprovide additional drive and/or magazine 140 slot capacity, so that amaximum configuration of one base module 110 and nine expansion modules120 has a total height of “21 RU,” or half of a standard equipment rack130. The single robot mechanism is configured to access all magazine 140slots and drives in the base module 110 and all expansion modules 120.

In the illustrative embodiment, each of the base module 110 and theexpansion modules 120 can house up to two half-height or one full-heightLTO5 tape drives. Each of the base module 110 and the expansion modules120 can also house two removable magazines 140, each having fifteencartridge slots. In some implementations, the storage library 100 can bedivided into partitions each associated with, for example, at least onedrive and at least one magazine 140. Each partition can be configured tobehave as an independent library, notwithstanding that all partitionsshare the single robotic mechanism (e.g., partitions can be commanded asindependent libraries for tape operations, while sharing many resourcesfor service and administration). Some implementations also include a“mailslot” 145 in the base module 110, as discussed below.

Some embodiments provide local and remote management of variousfunctions through graphical user interfaces (GUI). In oneimplementation, the local interface GUI is displayed on a seven-inch,front-mounted, touch-screen panel display 150. The remote interface maybe implemented as a browser-based interface (BUI), accessible byconnecting a web browser to the library's Internet protocol (IP)address.

Some embodiments are configured to be installable and serviceable by endcustomers to the greatest extent practical. For example, an installationwizard may be provided to simplify initial installation, a simple rackrail system for base modules 110 and expansion modules 120 will allowtwo people without any mechanical assistance (e.g. lift) to easilyinstall the modules on an equipment rack 130. In some such embodiments,most replaceable library components will be Customer Replaceable Units(CRUs) (i.e., as opposed to field replaceable units (FRUs), which areserviceable and/or replaceable only by trained technicians). Forexample, certain implementations allow almost all installation,maintenance, upgrades, and/or normal use of the storage library 100 tobe performed with only front and rear access to the equipment rack 130and few or no tools.

FIGS. 2A and 2B show rear and front views, respectively, of anillustrative base module 110′, according to various embodiments. Theillustrative base module 110′ may be an implementation of base module110 of FIG. 1. As shown, the base module 110′ includes a housing 203(e.g., a chassis) configured with rack mounts 205 for mounting to anequipment rack (e.g., as shown in FIG. 1). A rear face 207 and a frontface 209 are also shown as part of the housing 203. As discussed above,embodiments such as the one illustrated as base module 110′, aredesigned to facilitate customer serviceability. Accordingly, most of thereplaceable components are shown as accessible from the front and rearexterior of the base module 110′, which would be substantially exposedwhen mounted in a standard equipment rack.

Looking at the rear view of the base module 110′ in FIG. 2A, access isprovided to a robot CRU 210, one or more drive CRUs 220, and one or morepower supply CRUs 230. As will be described more fully below, the robotCRU 210 is configured to house the robotic mechanism and supportingcomponents (e.g., mechanical drive modules, control hardware andsoftware modules, configuration memory, etc.). Traditional storagelibrary systems typically are configured so that the robotic mechanismsare only serviceable by highly trained personnel, and even removing themechanism to send out for off-site servicing requires training,specialized tools, or the like. The ability to replace the entirerobotic mechanism and all its supporting components in a single CRU is anovel improvement over traditional implementations. For example,implementations allow a customer to simply pop out a broken robot CRU210 using a couple of thumb screws, slide in a replacement CRU, andreinitialize the system, without waiting for a technician totroubleshoot and fix any issues.

Embodiments of the drive CRUs 220 are media drive modules that can beremoved by an end consumer. Various implementations support standard,half-height or full-height tape drives. As described more fully below,the port in the drive for receiving a media cartridge faces into thebase module 110′, so that media cartridges can only be inserted and/orremoved by the robotic mechanism within the confines of the housing 203.In some implementations, one or more “external” media drives may beprovided to facilitate troubleshooting and the like.

Embodiments of the power supply CRUs 230 include any useful type ofpower supply components for supplying power to the base module 110′ andor to any other components (e.g., to one or more expansion modules 120(not shown)). For example, the power supply CRUs 230 can include powergenerators, power converters, power conditioners, back-up batteriesand/or other power duplication, switches, input and/or output ports,indicators, and the like. In some implementations, each power supply CRU230 includes a male, three-prong connector for interfacing with linepower and a main power switch. Some embodiments include a power supplyCRU 230 for each drive CRU 220 (i.e., if the base module 110′ has only asingle drive CRU 220, it may also only have a single power supply CRU230 to support the drive). In other embodiments, a second power supplyCRU 230 is used as a backup supply to the first power supply CRU 230,and may be coupled with a different power source.

In one implementation, the base module 110′ has slots for two powersupplies (e.g., two power supply CRUs 230). These can be implemented ascustom power supplies, for example, having an input voltage of 100-250volts AC at 50-60 Hertz, and an output voltage of twelve volts DCswitched plus five volts DC standby power. For example, the powersupplies may be sized to run two tape drives plus robotics and any othersensors, etc. (e.g., with or without redundancy). Typically, the basemodule 110′ has at least one power supply, even if no drives areincluded, to support the main processor, interface functionality (e.g.,the display 150), etc.

Looking at the front view of the base module 110′ in FIG. 2B, access isprovided to a display 150, one or more magazines 140, and a mailslot145. One or more indicators 255 may also be provided to show certainoperational states, and the like (note that the sizes, numbers,positions, etc. of the indicators shown are intended only to beillustrative). In various implementations, base module 110 has overalllibrary status indicators on the front and back of the module, alongwith a locate switch which activates the front and back locate LEDs;powered CRUs may have their own status indicators; hot-swappable CRUscan have indicators that show when the CRUs can be safely removed; powersupplies and tape drives can have additional indicators; an “AC present”indicator can be provided to stay on even when the storage library isoff (as long as AC power is connected). In one embodiment, a set ofprimary indicators include “locate,” “fault,” and “OK” indications. Nextto the primary indicators are secondary indicators specific for theoperator panel that indicate the status of the operator panel (e.g., anoperator panel CRU, if implemented as such).

Other types of indications and status can also be provided using thedisplay 150. Embodiments of the display 150 are used to facilitatevarious functionality through a local graphical user interface (GUI),including, for example, IO functions, service and diagnostic functions,etc. In one implementation, the display 150 is a seven-inch,front-mounted, touch-screen panel (e.g., an LCD touch panel display witha WVGA (wide VGA) 800×480 pixel screen equipped with a resistive orcapacitive touch-sensitive overlay).

Each magazine 140 can be configured to hold multiple (e.g., up tofifteen) cartridges in such a way as to be reliably accessed by therobotic mechanism. For example, the magazines 140 can be designed tohave features to aid in targeting, location, and or other functions ofthe robotic mechanism; features that securely hold the cartridges inplace, while allowing for easy release of the cartridges to a roboticgripper when desired; features to add strength to the magazines 140(e.g., to reduce sag, increase usable life, etc.) and/or to reduceweight; etc.

Embodiments of the mailslot 145 (or “Cartridge Access Port” (CAP))include a special type of magazine designed to act as a controlledinterface between the human user and the robotic mechanism. To add orremove cartridges from the storage library, a user ejects the mailslot145 from the base module 110′ and is presented with a number ofcartridge slots (e.g., four “Import/Export cells” (“I/E cells”)). Theuser can then insert cartridges into, or remove cartridges from, theseslots without interfering with robotic mechanism's operations. In someimplementations, the robotic mechanism is used to activate a latchinternal to the base module 110, thereby allowing the user to remove themailslot 145 only when the robotic mechanism is in an appropriatecondition (e.g., parked in the robot CRU 210). Certain embodimentshaving data partitions (as discussed above) only allow one partition ata time to make use of the mailslot 145.

FIGS. 3A and 3B show rear and front views, respectively, of anillustrative expansion module 120′, according to various embodiments.The illustrative expansion module 120′ may be an implementation ofexpansion module 120 of FIG. 1. As shown, the expansion module 120′includes a housing 303 (e.g., a chassis) configured with rack mounts 305for mounting to an equipment rack (e.g., as shown in FIG. 1). A rearface 307 and a front face 309 are also shown as part of the housing 303.As with the base module 110′ of FIGS. 2A and 2B, the expansion module120′ is designed to facilitate customer serviceability. Most of thereplaceable components are shown as accessible from the front and rearexterior of the expansion module 120′, which would be substantiallyexposed when mounted in a standard equipment rack.

In the embodiment shown, various aspects of the expansion module 120′are similar or identical to the base module 110′. For example,embodiments of the expansion module 120′ do not typically have a robotCRU 210, display 150, or mailslot 145, as they are configured to exploitthat functionality from the base module 110′ components. However, likethe base module 110′, the expansion module 120′ includes one or moredrive CRUs 220 and one or more power supply CRUs 230 configured to beaccessed from the rear side of the expansion module 120′, and one ormore magazines 140 configured to be accessed from the front side of theexpansion module 120′. In some embodiments, the drive CRUs 220, powersupply CRUs 230, and/or magazines 140 of the expansion module 120′ arethe same as those implemented in the base module 110′.

Because of the lack of certain features in embodiments of the expansionmodule 120′ (e.g., there may be no robot CRU 210, no main processor,etc.), expansion module 120′ power requirements may be different fromthose of the base module 110. In certain implementations, the expansionmodules 120′ still have slots for two power supplies (e.g., two powersupply CRUs 230), which can be implemented as the same power suppliesused in the base module 110 (e.g., to avoid having to support or sourcemultiple types of power supplies). However, the power supplies of thebase module 110 may provide more power than is needed to runconfigurations of the expansion modules 120′. For example, a singlepower supply may be able to support an expansion module 120′ even withtwo drives, and it is possible to implement an expansion module 120′with no drives and no power supplies. Alternatively, two power suppliesmay still be used, for example, to provide redundancy.

As discussed above, the base module 110′ and expansion modules 120′include a number of components that can be designed for customerreplaceability, including the robot CRU 210, drive CRUs 220, powersupply CRUs 230, and magazines 140. It is worth noting that, even thoughthese components may be accessible and replaceable by customers,embodiments may still be configured to prevent (or mitigate) undesirableinterference with those components. As one example, those replaceablecomponents typically are installed in a physically secure manner (e.g.,using latches, thumbscrews, removable faceplates, and/or othertechniques) to provide relatively easy access when needed, whilemitigating inadvertent access (e.g., accidental removal of a magazine140 during operation). As another example, certain embodiments may allowa drive CRU 220 to be removed during operation of the storage system, solong as the drive is not actively in use (e.g., by using a drive ejector park command, or other technique). As still another example, removalof the robot CRU 210 or magazines 145 may be prevented until certainoperations have been completed (e.g., the robotic mechanism is parkedwithin the base module 110′, etc.).

The embodiments of storage library systems and components describedabove are intended to provide clarity to the invention and someillustrative implementations. Modifications can be made withoutdeparting from the scope of inventions. For example, certain logical(e.g., throughput) and/or physical (e.g., pass-through) expansionfunctionality involves modifications to the storage libraryconfigurations. Further, much of the functionality of storage systems,like those discussed above with reference to FIGS. 1-3B, is facilitatedby the robotic mechanism. As discussed above, the robotic mechanism isused to locate cartridges and ferry them between magazine slot locationsand media drives. FIGS. 4A and 4B illustrate two views of anillustrative robot mechanism implemented as part of a robot CRU 210. Theillustrations and descriptions of the robotic mechanism are highlysimplified and represent only on possible type of implementation.Accordingly, they are intended only to add clarity and context andshould not be construed as limiting the scope of the invention.

Turning to FIG. 4A, a view is shown looking down on the underside of anillustrative robot CRU 210′, according to various embodiments. The robotCRU 210′ may be an implementation of the robot CRU 210 of a base module110, as discussed with reference to FIG. 2A. The robot CRU 210′ includesa chassis 405 that houses a Z-platform assembly 410, an X-drive assembly415, a hand assembly 420, a Z-drive assembly 425, and a robot controlassembly 430.

In the implementation shown, the robotic mechanism is configured to movefrom its “home” position in the robot CRU 210′ of the base module 110′down and/or over to any magazine 145 slot or drive in the base module110′ or an expansion module 120′. To accomplish this type of motion, thehand assembly 420 of the robotic mechanism moves in at least a “Z”direction (as used herein, the +Z direction is up towards the homeposition in the robot CRU 210, and the −Z direction is down towards thebottom-most magazine slots of the bottom-most expansion module 120′) andan “X” direction (as used herein, the +X direction is towards the frontside of the base module 110′ or expansion modules 120′, and the −Xdirection is towards the rear side of the base module 110′ or expansionmodules 120′).

The hand assembly 420 is coupled with the Z-platform assembly 410, whichcan be moved in the Z-direction (i.e., raised and lowered) by theZ-drive assembly 425. The hand assembly 420 is also able to move alongthe Z-drive assembly 425 in the X-direction by the X-drive assembly 415(e.g., along rails that are substantially perpendicular to theZ-directional axis). The Z-drive assembly 425 and X-drive assembly 415may include any hardware for providing the desired movements, such ascables, gears, belts, rails, wheels, bearings, etc. Embodiments provideother types of motion in other ways. Some embodiments of the handassembly 420 are coupled to the Z-platform assembly 410 via a “wrist”mechanism (not shown) that provides motion in a yaw direction (i.e.,around the Z-directional axis). Some embodiments of the hand assembly420 further provide radial movement from the Z-directional axis. Forexample, a grabber mechanism can “reach out” in a radial direction thatis determined by the yaw (rotational) orientation provided by the wristmechanism.

These various types of motion of the robotic mechanism, as well as otherfunctionality of the robotic mechanism, are handled at least in part bythe robot control assembly 430. Embodiments of the robot controlassembly 430 are effectively the “brains” of the robotic mechanism,including electronic components used to store calibration informationfor the robotic mechanism, control movements of the robotic mechanism,read and/or decipher sensor information retrieved from the roboticmechanism, etc. For example, if data from a particular cartridge isdesired, the robot control assembly 430 may direct the robotic mechanismto move to the magazine slot associated with that cartridge, verifypresence of the cartridge, retrieve the cartridge from the magazine,ferry the cartridge to a drive, and release the cartridge into thedrive.

For added clarity, FIG. 4B shows another view looking up at theunderside of an illustrative robot CRU 210′ with the Z-platform assembly410 partially lowered, according to various embodiments. As illustrated,the Z-platform assembly 410 may not have a solid platform, and mayinstead be implemented as a carriage having a number of structuralmembers (e.g., rails, supports, etc.). In the particular embodimentshown, the Z-drive assembly 425 includes motors and gearing that drive abullwheel. The Z-platform assembly 410 is coupled with the bullwheelusing a cable and pulley system. For example, cabling 440 is attached ateach corner of the Z-platform assembly 410. The four cables 440 passthrough pulleys and wrap around the bullwheel. Turning the bullwheel inone direction or the other adds slack to, or removes slack from, thecables 440, causing the Z-platform assembly 410 to be raised or lowered.Once in its desired Z-position (or while moving to that position), theX-drive assembly 415 can be used to move the hand assembly 420 (e.g.,along rails of the Z-platform assembly 410) to a desired X-location.Once in its desired X-Z-position (or while moving to that position), thehand assembly 420 can be turned (e.g., using a wrist mechanism) to adesired rotational orientation (e.g., to face a cartridge slot or amedia drive, to provide a desired angle for use of a sensor, etc.). Ifdesired, a gripper mechanism may then be used to reach out (i.e.,radially) from that X-Z-position and rotational orientation (e.g., tograb or release a cartridge). Some implementations of hand and grippermechanisms are described in U.S. patent application Ser. No. 13/348,486,filed on Jan. 11, 2012, titled “Ratcheting Gripper for a StorageLibrary,” which is hereby incorporated by reference in its entirety.

Multi-Robot Embodiments

Performance of various cartridge operations, such as pick-and-placeoperations, inventory and auditing operations, and the like, involvemoving the hand assembly 420 to one or multiple desired locations. Forexample, placing a cartridge into a media drive can involve moving thehand assembly 420 to the slot location of the cartridge in a magazine,picking the cartridge from the slot (e.g., by extending the grippermechanism to engage with the cartridge and retracting the grippermechanism with the cartridge engaged), moving the hand assembly 420 withthe engaged cartridge to the media drive location, and placing thecartridge in the drive (e.g., by extending the gripper mechanism todisengage with the cartridge in the drive slot and retracting thegripper mechanism without the cartridge). Each of these stages involvesmovement of the hand assembly 420 and takes a discrete amount of time.Accordingly, the throughput of the media library can be limited at leastin part by the time it takes to move the hand assembly 420 to eachlocation. In some embodiments, multiple robotic mechanisms are usedconcurrently, each with its own hand assembly 420.

FIG. 5 shows a partial illustrative multi-robot CRU 500 that has twoZ-platform assemblies 410, each partially lowered, according to variousembodiments. The illustrated Z-platform assemblies 410 are implementedas a carriage having a number of structural members (e.g., rails,supports, etc.), and are shown without certain components (e.g.,respective X-drive assemblies 415) to avoid over-complicating thefigure. As will be shown in more detail below, the Z-drive assembly 425of the multi-robot CRU 500 includes motors and gearing that drive twobullwheels in a manner that can independently control the Z position ofeach Z-platform assembly 410. Each Z-platform assembly 410 is coupledwith the bullwheel using a cable and pulley system. Certainimplementations couple each Z-platform assembly 410 with its own cabling440, but some of the pulley system (e.g., certain wheels, guides, etc.)can be shared by the two Z-platform assemblies 410. In the illustratedembodiment, cabling 440 is attached near each corner of one side andnear the center of the other side of each Z-platform assembly 410,though other implementations can use different cabling 440 arrangements(e.g., like the four-corners arrangement illustrated in FIG. 4B). Thecabling 440 passes through pulleys and wraps around respectivebullwheels. Turning each bullwheel in one direction or the other addsslack to, or removes slack from, the cabling 440, causing eachZ-platform assembly 410 to be raised or lowered.

Once in their desired Z-positions (or while moving to that position),each X-drive assembly 415 can be used to move a respective hand assembly420 (e.g., along rails of the Z-platform assembly 410) to a desiredX-location. Once in their desired X-Z-positions (or while moving tothose positions), each hand assembly 420 can be turned (e.g., usingwrist mechanisms) to desired rotational orientations (e.g., to face acartridge slot or a media drive, to provide a desired angle for use of asensor, etc.). If desired, a gripper mechanism may then be used to reachout (i.e., radially) from the X-Z-positions and rotational orientations(e.g., to grab or release a cartridge).

Independent and concurrent availability of multiple robotic assembliescan provide a number of features. One category of such features canincrease throughput of the storage library. As one example, multiplerobotic assemblies can be used to perform pick-and-place operations(e.g., moving a cartridge from a slot to a drive, etc.) on multiplecartridges concurrently. As another example, one robotic assembly of themultiple robotic assemblies can be used to perform a pick-and-placeoperation while another robotic assembly of the multiple roboticassemblies can be used to perform auditing or inventory functions (e.g.,cataloging contents of slots, etc.). As another example, one roboticassembly of the multiple robotic assemblies can wait for un-mounting andunloading of a drive while another robotic assembly of the multiplerobotic assemblies goes to retrieve a next cartridge. As anotherexample, one robotic assembly of the multiple robotic assemblies can beused to load and/or unload cartridges to and/or from the mailslot 145while another robotic assembly of the multiple robotic assemblies can beused to perform pick-and-place operations. Another category of suchfeatures can provide redundancy in the storage library. In one example,the multiple robotic assemblies allow one robotic assembly of themultiple robotic assemblies to be used, or to remain in use, whenanother robotic assembly of the multiple robotic assemblies becomesnon-operational (e.g., electrically and/or mechanically).

Performance of these and other multi-robot functions can involve varioustypes of contention systems (e.g., hardware and/or software). Thecontention systems can be used to avoid either or both of physicalcontentions (e.g., collisions between the multiple robotic assemblies,etc.) and logical contentions (e.g., directing multiple roboticassemblies to perform conflicting tasks or to perform tasks in anundesirable order, etc.). In performance of these functions, thecontention systems can include any suitable sensing, feedback, and/orother functionality for real-time and/or predictive collision avoidance.In some implementations, contention functionality involves schedulingand/or queuing of tasks. For example, multiple pick-and-place operationscan be queued, scheduled, and assigned to particular ones of themultiple robotic assemblies in such a way that avoids collisions betweenthe multiple robotic assemblies and/or maximizes throughput (e.g.,maximizes the number of operations that can be concurrently performedwithout physical or logical collision). In one illustrative scenario, afirst cartridge is removed from a drive and a next cartridge is loadedin the drive. Without a contention system, it is likely that the firstcartridge would be retrieved and put away into an appropriate magazineslot, after which the next cartridge would be retrieved and loaded intothe drive. However, there may be no reason to wait to put away the firstcartridge before loading the next. Accordingly, using contentiontechniques (e.g., appropriate task scheduling and collision avoidance),a first robotic assembly can wait for the drive to un-mount and canremove the first cartridge from the drive, while a second roboticassembly can retrieve the next cartridge. After removing the firstcartridge, the first robotic assembly can move out of the way of thepath of the second robotic assembly until the second robotic assemblyhas retrieved the next cartridge and has loaded the next cartridge intothe drive. The two robotic assemblies can then move as appropriate toallow the first robotic assembly to put the first cartridge away into anappropriate magazine slot. This type of contention management canappreciably increase throughput. Many other types of contentionmanagement techniques can be used in other scenarios.

For the sake of added clarity, FIGS. 6A and 6B show views of anillustrative storage library environment 600 having multiple roboticassemblies, according to various embodiments. The storage libraryenvironment 600 a of FIG. 6A has two robotic assemblies positioned indifferent portions of the storage library environment 600. For example,one robotic assembly is performing an operation in a bottom-mostexpansion module 120 of the storage library environment 600, whileanother is concurrently performing an operation in a higher expansionmodule 120 of the storage library environment 600. Alternatively, onerobotic assembly is idle in a bottom-most expansion module 120 of thestorage library environment 600 (e.g., kept out of the way until neededfor redundancy purposes), while another is performing an operation in ahigher expansion module 120 of the storage library environment 600. Thestorage library environment 600 b of FIG. 6B has two robotic assembliespositioned vertically adjacent to each other in the storage libraryenvironment 600.

FIG. 7 shows an exploded view of an illustrative configuration of apartial Z-drive assembly 700 for use with multiple robotic assemblies,according to various embodiments. The partial Z-drive assembly 700includes two drive sub-assemblies, each configured to independentlycontrol the Z position of a respective robotic assembly. For example,each sub-assembly includes a bullwheel 710, a drive motor 720, and adrive gear 730. Actuating a first drive motor 720 a to turn in adirection, causes a first drive gear 730 a to turn, which turns a firstbullwheel 710 a, thereby adding or taking up slack in cabling (notshown) wrapped around the bullwheel 710 a. Actuating a second drivemotor 720 b to turn in a direction, causes a second drive gear 730 b toturn, which turns a second bullwheel 710 b, thereby adding or taking upslack in cabling (not shown) wrapped around the bullwheel 710 b. In thisway, one or more robotic assemblies coupled to the cabling of eachbullwheel 710 can be independently moved in the Z direction.

Vertical Pass-Through Embodiments

Some storage libraries are configured to operate within particulardimensions. For example, as illustrated in FIG. 1, a storage library canbe configured to fit in a standard equipment rack and may or may not bevertically expandable. The dimensions of the storage library can definea maximum amount of space that is available in the storage library forstoring cartridges, media drives, and other types of components. Forexample, one illustrative configuration includes a base module 110 andthree expansion modules 120, having eight magazines 140 with storage forfifteen cartridges each, and a mailslot 145 configured to hold up tofive cartridges (i.e., space to store up to 125 cartridges total). Asdescribed above, some embodiments permit expansion modules 120 to beadded to increase the size of the storage library.

However, some implementations have limited or no expandability.Accordingly, adding to the size of the library may involve purchasing anadditional library. While the additional library can increase the totalamount of available library space, it can also effectively segregate thelibrary into two distinct environments. For example, a cartridge fromone library cannot be used in the environment of the other library(e.g., moved to the other library, accessed via a media drive of theother library, etc.) when the two libraries are physically separateentities. As such, embodiments include vertical pass-throughfunctionality to facilitate movement of a cartridge from one physicallibrary environment into a vertically adjacent physical libraryenvironment.

FIG. 8 shows an upper physical library environment 800 and a lowerphysical library environment 850 configured for vertical pass-throughfunctionality, according to various embodiments. For the sake ofillustration, both physical library environments are shown as a basemodule and a set of expansion modules, similar to those described above.Similar techniques can be applied to other physical library environmentswithout departing from the scope of embodiments.

The upper physical library environment 800 includes a pass-through plate810 and a robotic assembly 830. The pass-through plate 810 and roboticassembly 830 can be configured in any manner that permits a hand of therobotic assembly 830 to drop below a bottom plane of the upper physicallibrary environment via the pass-through plate 810. For example, asillustrated, the robotic assembly 830 is configured with its handpositioned below structure supporting the hand, and the pass-throughplate 810 includes an opening large enough to allow the hand to dropthrough the opening.

The lower physical library environment 850 includes a shared slot 820and a robotic assembly 840. The shared slot 820 is positioned in amanner that is accessible to both robotic assembly 840 (from the lowerphysical library environment 850) and to robotic assembly 830 (from theupper physical library environment 800 via the pass-through plate 810).For example, as illustrated, robotic assembly 840 is configured with itshand positioned above structure supporting the hand to facilitate thehand reaching the shared slot 820. In one implementation, the sharedslot 820 is a single pass-through slot (e.g., similar or identical to amagazine slot) that simply acts as a way station for a passed cartridge.In another implementation, the shared slot 820 is one slot in a magazineof the lower physical library environment 850. In yet anotherimplementation, the shared slot 820 is a slot of a media drive. Forexample, the media drive can be used directly by both physical libraryenvironments. This may be desirable, for example, when additional drivesare desired, if the drive is a specialized or particularly expensivedrive (i.e., permitting that drive to be shared by two libraries cansave the end consumer cost). In still other implementations, the sharedslot 820 can be any other suitable type of slot or mechanism forsecuring a passed cartridge in a manner that can be retrieved by eitherrobotic assembly.

The illustrated configuration is only one of many possibleimplementations that fall within the scope of embodiments. According toanother illustrative implementation, the lower physical libraryenvironment 850 includes the pass-through plate 810, the upper physicallibrary environment 800 includes the shared slot 820, and roboticassembly 840 of the lower physical library environment 850 is configuredto reach through the pass-through plate 810 to pick or place passedcartridges from or into the shared slot 820. According to yet anotherillustrative implementation, the pass-through plate 810 is not present,and the “floor” of the upper physical library environment 800 iseffectively open for robotic assembly 830 to pass into the lowerphysical library environment 850 (e.g., or partially open in a mannerdifferent from the one illustrated). In some such implementations, theshared slot 820 can be a designated slot or any slot of any magazine ormedia drive of the lower physical library environment 850. In other suchimplementations, vertical pass-through functionality can be combinedwith certain multi-robot functionality described above. For example,contention techniques can be used to perform concurrent operations inthe lower physical library environment 850 by using robotic assembly 840only in the lower physical library environment 850 and using roboticassembly 830 in both physical library environments. According to stillother implementations, one or both of the robotic assemblies can includeadditional mechanisms to allow the hand to reach further into anotherlibrary environment. For example, in addition a wrist mechanism allowingthe hand to rotate the wrist mechanism can also be configured to extendthe hand away from its supporting structure to move further in the Zdirection than the support structure would otherwise allow. Additionalimplementations can include moving only portions of the hand (e.g., onlythe gripper) in certain ways, tilting the hand, etc.

For the sake of added clarity, FIGS. 9A and 9B show verticalpass-through functionality in context of a stacked storage libraryenvironment 900, according to various embodiments. As illustrated, theupper physical library environment 800 is stacked on top of the lowerphysical library environment 850 with the opening of the pass-throughplate 810 positioned directly over the shared slot 820. As describedwith reference to FIG. 8, this permits the robotic assembly 830 of theupper physical library environment 800 to effectively reach through thepass-through plate 810 in to the lower physical library environment 850to facilitate pass-through functionality via the shared slot 820. FIG.9A shows robotic assembly 830 reaching through the pass-through plate810 opening to place a cartridge into the shared slot 820 (with roboticassembly 840 effectively moved out of the way or concurrently performinganother operation). FIG. 9B shows robotic assembly 840 retrieving thecartridge from the shared slot 820 (with robotic assembly 830effectively moved out of the way or concurrently performing anotheroperation).

In addition to providing physical vertical pass-through functionality,some embodiments further include supporting logical functionality. Insome implementations, host-level (or any other suitable level of)software is used to make at least one of the libraries aware of andcapable of exploiting the shared slot 820. For example, each library ismade aware of the shared slot 820 and is configured to utilize theshared slot to pass cartridges back and forth among the libraries. Thesupporting logical functionality can include notifying one or bothlibraries when a cartridge is present in the shared slot 820; providinga shared inventory of cartridges so that each library can be made awareof cartridges in both libraries; providing shared access to otherresources (e.g., media drives); and/or any other suitable logicalfunctionality.

Horizontal Pass-Through Embodiments

As described above, some storage libraries are configured to operatewithin particular dimensions, such as some or all of an equipment rack.Even storage libraries that are vertically expandable to take up theentire equipment rack, however, are limited by the overall dimensions ofthe equipment rack. For example, a standard equipment rack may supportapproximately six vertical feet of equipment (e.g., 42 standard rackunits, where each rack unit is approximately 1.75-inches high).Referring generally to FIG. 1, a maximum configuration of anillustrative embodiment includes one base module 110 (supporting 35cartridges) and nine expansion modules 120 (each supporting 30cartridges), with a total height of “21 RU,” or half of a standardequipment rack 130. Stacking two of these illustrative configurationsinto a single equipment rack supports a maximum of 610 cartridges.

To support additional cartridges, the environment may have to expand toa horizontally adjacent equipment rack, and some embodiments includehorizontal pass-through functionality, accordingly. Implementing aneffective horizontal pass-through can be difficult for a number ofreasons. Passing from one vertical storage library to another mayinvolve active horizontal pass-through mechanisms for physicallyferrying a cartridge between the horizontally adjacent libraries.However, reliable ferrying can involve a number of considerations. Oneconsideration is maintaining a stable pick and place environment thatcan be reliably accessed by the robotic mechanisms of each libraryenvironment. Another consideration is orienting the cartridgeappropriately when passed. For example, each library environment may beconfigured so that cartridges are placed in slots facing in a particulardirection (e.g., facing outward) to facilitate pick and place operationsby their respective robotic assemblies. When passing from one side(e.g., the right side) of a first library to the opposite side (e.g.,the adjacent left side) of a second library, the respective slotorientations may be different (e.g., 180-degrees different).Accordingly, it may be desirable for the horizontal pass-throughmechanism to rotate the cartridge as appropriate during ferrying (e.g.,or directly before or after ferrying).

Another consideration is accommodating different (and potentiallyshifting) horizontal separations between adjacent libraries. For thesake of illustration, FIGS. 10A and 10B show storage libraryenvironments 1000, each having storage libraries 1010 on respective,horizontally adjacent equipment racks 130. In FIG. 10A, the twoequipment racks 130 are spaced very close together (as indicated byarrows 1020 a). In FIG. 10B, the two equipment racks 130 are spacedfarther apart (as indicated by arrows 1020 b). In some environments,different equipment racks 130 are located at different horizontalspacings from each other (e.g., first and second equipment racks 130 areclose together, while the second and a third are far apart). Further, incertain environments, the equipment rack 130 locations can shiftslightly relative to each other, due, for example, to vibrations.

Accordingly, embodiments of horizontal pass-through assemblies describedherein can accommodate multiple horizontal spacings. Further, asdescribed below, some implementations accommodate multiple horizontalspacings with simple installation and little or no tooling. For example,FIG. 11 shows a partial library environment 1100 having an illustrativehorizontal pass-through assembly 1110 between two, horizontally adjacentstorage libraries 1010 spaced apart by a horizontal span 1020. Theillustrative horizontal pass-through assembly 1110 is coupled with eachstorage library 1010 and includes a carriage for passing cartridgesbetween the two libraries.

FIG. 12A shows a simplified block diagram of a horizontal pass-throughassembly 1200, according to various embodiments. For the sake ofcontext, two, horizontally adjacent storage libraries 1010 are shown,spaced apart by a horizontal span 1020. The horizontal pass-throughassembly 1200 can be used as the horizontal pass-through assembly 1110of FIG. 11. Embodiments of the horizontal pass-through assembly 1200provide a number of functions. One function of embodiments of thehorizontal pass-through assembly 1200 is to ferry cartridges securelyfrom one storage library to a horizontally adjacent storage library.This can include ferrying from one secure pick-and-place location at onelibrary to another secure pick-and-place location. This can also includereorienting (e.g., rotating) the cartridge, as appropriate, for use byeach library. Another function of embodiments of the horizontalpass-through assembly 1200 is to easily adjust to a range of horizontalspacings.

The horizontal pass-through assembly 1200 includes a library securementassembly 1230 comprising a first portion configured to physically couplewith the first storage library 1010 a at a first side of the librarysecurement assembly 1230, and a second portion configured to physicallycouple with the second storage library 1010 b at a second side of thelibrary securement assembly 1230, in such a way that a horizontal spanbetween the first and second portions can be adjusted over a definedrange of possible horizontal spans 1020 between the storage libraries1010. The horizontal pass-through assembly 1200 also includes a carriage1210 configured to receive a media cartridge and a drive assembly 1220.The drive assembly 1220 couples the carriage 1210 with the librarysecurement assembly 1230. Embodiments of the drive assembly 1220actively drive the carriage 1210 between first and second pick-and-placelocations at respective sides of the library securement assembly 1230along a path 1220 that dynamically complies with (i.e., accommodates)the horizontal span between the first and second portions of the librarysecurement assembly 1230. In some embodiments, the drive assembly 1230includes components to electrically (e.g., communicatively) couple thehorizontal pass-through assembly 1200 with one or more storage libraries1010. Certain embodiments further include additional components, likeprocessors and/or any other suitable component.

FIG. 12B shows another view of the horizontal pass-through assembly 1200of FIG. 12A, to illustrate certain features of some implementations. Asdescribed above, embodiments include a drive assembly 1220 that activelydrives the carriage 1210 between first and second pick-and-placelocations at respective sides of the library securement assembly 1230.As illustrated, the drive assembly 1220 can include a first pivotlocation 1250 a around which the carriage is driven (e.g., in an arc oralong any suitable path, for example, as described below). The firstpivot location 1250 a can, for example, be the central axis of a drivegear or implemented in any other suitable fashion. The first portion ofthe library securement assembly 1230 a can be configured to physicallycouple with the first storage library 1010 a in such a way that definesa second pivot location 1250 b that is coupled with the first pivotlocation 1250 a and separated from the first pivot location 1250 a by afirst distance 1270 a. The second portion of the library securementassembly 1230 b is configured to physically couple with the secondstorage library 1010 b in such a way that defines a third pivot location1250 c that is coupled with the first pivot location 1250 a andseparated from the first pivot location 1250 a by a second distance 1270b. The second pivot location 1250 b and the third pivot location 1250 care separated by a third distance 1270 c that is defined by thehorizontal span 1020, such that, as the horizontal span 1020 isadjusted, the third distance 1270 c changes accordingly, and the firstand second distances (1270 a and 1270 b) remain substantially static. Insome implementations, the first and second distances (1270 a and 1270 b)are substantially equal, so that the path 1220 dynamically complies toaccommodate the horizontal span 1020 between the first and secondportions by maintaining the first pivot location 1250 a substantiallycentered between the second and third pivot locations (1250 b and 1250c) regardless of the horizontal span 1020. For example, the first,second, and third distances (1270 a, 1270 b, and 1270 c) can form anisosceles triangle. In other implementations, the first and seconddistances (1270 a and 1270 b) can be adjusted (e.g., manually) toaccommodate differences in library installations, for fine adjustment ofthe assembly, etc.

In some implementations, when the first portion is coupled with thefirst storage library 1010 a, the second pivot location 1250 b isseparated from the first pick-and-place location (e.g., and/or from aparticular library installation feature or other suitable location) by afourth distance 1270 d, so that the first and fourth distances (1270 aand 1270 d) form two sides of a first triangle. When the second portionis coupled with the second storage library 1010 b, the third pivotlocation 1250 c is separated from the second pick-and-place location(e.g., or other suitable location) by a fifth distance 1070 e, so thatthe second and fifth distances (1270 b and 1270 e) form two sides of asecond triangle. In such implementations, the first pivot location 1250a can be coupled with each of the second and third pivot locations (1250b and 1250 c) in such a way that the third side of the first triangle1070 f and the third side of the second triangle 1070 g aresubstantially equal in length regardless of the horizontal span 1020.For example, this permits the first pivot location 1250 a (e.g., thecentral axis that defines the path 1220 over which the carriage 1210travels) to dynamically comply with changes in the horizontal span 1020.

FIGS. 13 and 14 show two views of an illustrative implementation of ahorizontal pass-through assembly 1300, according to various embodiments.Embodiments of the horizontal pass-through assembly 1300 includestructure shaped to provide a cam path 1320, which the carriage 1210 canfollow to travel from one storage library on one side of the horizontalpass-through assembly 1300 to another storage library on the other sideof the horizontal pass-through assembly 1300. As illustrated, thehorizontal pass-through assembly 1300 can couple with each of twostorage libraries using respective library securements 1330. Forexample, each library securement 1330 includes securing structure (e.g.,holes, pins, thumb screws, hooks, magnets, or any other suitableelements) for securing the respective library securement 1330 to one ormore features of the respective storage library. Various types ofsecurement extenders 1335 can be included to permit expansion of thehorizontal pass-through assembly 1300 into various horizontal spacings.In some implementations, a cam path extender 1325 is included to extendthe cam path 1320 to accommodate horizontal expansion of the horizontalpass-through assembly 1300. For example, as illustrated, edges of thelibrary securements 1330 and the cam path extender 1325 can togethereffectively define the cam path 1320.

According to some embodiments, the carriage 1210 is coupled with a swingarm 1315 and a tensioner 1350 (e.g., a spring or other suitable devicefor providing constant or adjustable tension). A cam follower 1410(visible in FIG. 14) can be designed to ride along the cam path 1320(e.g., along certain edges of the library securements 1330 and the campath extender 1325. The swing arm 1315 and the tensioner 1350 can extendto allow the cam follower 1410 to ride along the cam path 1320 intension, even as a distance between an axis of rotation of the swing arm1315 and the cam path 1320 changes. In some implementations, a drivemotor 1340 is coupled with the swing arm 1315 via a drive gear 1345, sothat actuation of the drive motor 1340 can turn the drive gear 1345,thereby swinging the swing arm 1315 and the carriage 1210 from one sideof the horizontal pass-through assembly 1300 to the other side of thehorizontal pass-through assembly 1300 along the cam path 1320.

The embodiment shown in FIGS. 13 and 14 is intended to illustrate onepossible implementation, but many different variations can be madewithout departing from the scope of other embodiments. For example, theillustrated embodiment provides means for ferrying cartridges securelyfrom one storage library to a horizontally adjacent storage library byreceiving a cartridge in the carriage 1210 and swinging the carriage1210 about the cam path 1320. Other embodiments can include any suitablecarriage means for securely receiving one or more cartridges, anysuitable means for moving the carriage means from one side of thehorizontal pass-through assembly 1300 to the other, any suitable campath 1320, any suitable means for causing the carriage means to followthe cam path 1320, etc. Further, the illustrated embodiment reorientsthe cartridge as it is ferried from one side of the horizontalpass-through assembly 1300 to the other by swinging the carriage 1210around an axis. Other embodiments can include any suitable means forreorienting the cartridge, including any active and/or passive means forrotating the cartridge and/or the carriage 1210 before, during, and/orafter ferrying of the cartridge from one side of the horizontalpass-through assembly 1300 to the other. Even further, the illustratedembodiment adjusts to a range of horizontal spacings using a number ofcomponents, including securement extenders 1335, the cam path extender1325, the extendable swing arm 1315, and the extendable tensioner 1350.Other embodiments include other means for maintaining a usable cam path1320 and means for maintaining the axis of rotation of the swing arm1315 in a substantially proportionally fixed location with respect tothe overall horizontal span of the horizontal pass-through assembly 1300(e.g., substantially in the center) as the horizontal span of thehorizontal pass-through assembly 1300 is adjusted. Still otherembodiments e.g., that do not use the same arrangement of swing arm 1315and cam path 1320 can include any other suitable means for extending thehorizontal span of the horizontal pass-through assembly 1300 in thecontext of their respective carriage means, etc.

Additionally, some implementations can automatically adjust to anappropriate horizontal span. For example, FIGS. 13 and 14 show anembodiment having library securements 1330 that can be manually pulledapart to accommodate different horizontal spans between storagelibraries. Alternate embodiments can include motorized, spring-loaded,or otherwise automatic expansion functionality. In one implementation,an additional motor is provided to drive active securement extenders1335. When installing the horizontal pass-through assembly 1300, forexample, a first side (e.g., a first library securement 1330) is securedto features of one storage library. The additional motor can then beactivated to drive the active securement extenders 1335 across the spanuntil the other library is reached, at which point the other librarysecurement 1330 can either be manually secured, automatically secured,held in place by tension, etc.

For the sake of further illustration, FIGS. 15A and 15B show views 1500of a horizontal pass-through assembly 1200 installed in an illustrativelibrary environment. Each view is a cut-away view looking down on thelibrary environment, so that a portion of the structure and a portion ofa storage magazine for each of two, horizontal storage libraries 1010provide context. In FIG. 15A, the two storage libraries 1010 arepositioned close together, and the horizontal pass-through assembly 1200a is horizontally compacted to fit the close spacing. In FIG. 15B, thetwo storage libraries 1010 are positioned farther apart, and thehorizontal pass-through assembly 1200 b is horizontally expanded to fitthe larger spacing. In both of FIGS. 15A and 15B, an associated cam path1320 is shown to illustrate that the cam path adjusts along with theadjustments to the horizontal span of the horizontal pass-throughassembly 1200.

The horizontal pass-through assembly 1200 can be installed in thelibrary environment in any suitable manner. For example, FIG. 16 showsan installation 1600 that includes a dedicated horizontal pass throughmodule 1610 that can be added to each storage library. The horizontalpass through module 1610 can include mounting locations for couplingwith library securements of the horizontal pass-through assembly 1200and an opening to permit movement of the horizontal pass-throughassembly 1200 carriage (e.g., to allow the swing arm to swing around itsaxis). The opening can be sized to facilitate different amounts ofmovement for different horizontal spacings. For example, in theconfiguration of horizontal pass-through assembly 1300 illustrated inFIGS. 13 and 14, the swing radius may increase as the horizontal span ofthe assembly increases. Certain implementations of the horizontal passthrough modules 1610 can also include additional features, such as anopen vertical pathway (e.g., no top structure and an open bottomstructure, as illustrated) to facilitate vertical movement of a roboticmechanism through the horizontal pass through module 1610 to expansionmodules below. In some implementations, the horizontal pass throughmodule 1610 can be part of an expansion module; can include or supportone or more magazines, additional cartridge storage slots, or drives;etc.

In addition to providing physical horizontal pass-through functionality,some embodiments further include supporting logical functionality. Insome implementations, host-level (or any other suitable level of)software is used to make the libraries aware of and capable ofexploiting the horizontal pass-through assembly and/or module. This caninclude electrically coupling one or both libraries (e.g., theirrespective main processors) to the horizontal pass-through assembly toallow one or both libraries to control the drive motor and/or otherfunctions of the horizontal pass-through assembly. Other supportinglogical functionality can include notifying one or both libraries when acartridge is delivered to and/or received from the horizontalpass-through assembly; providing a shared inventory of cartridges sothat each library can be made aware of cartridges in both libraries;providing shared access to other resources (e.g., media drives); and/orany other suitable logical functionality.

The methods disclosed herein comprise one or more actions for achievingthe described method. The method and/or actions may be interchanged withone another without departing from the scope of the claims. In otherwords, unless a specific order of actions is specified, the order and/oruse of specific actions may be modified without departing from the scopeof the claims.

The various operations of methods and functions of certain systemcomponents described above may be performed by any suitable meanscapable of performing the corresponding functions. The means may includevarious hardware and/or software component(s) and/or module(s),including, but not limited to a circuit, an application specificintegrated circuit (ASIC), or processor. For example, logical blocks,modules, and circuits described may be implemented or performed with ageneral purpose processor, a digital signal processor (DSP), an ASIC, afield programmable gate array signal (FPGA), or other programmable logicdevice (PLD), discrete gate, or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general purpose processor may be a microprocessor,but in the alternative, the processor may be any commercially availableprocessor, controller, microcontroller, or state machine. A processormay also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The steps of a method or algorithm or other functionality described inconnection with the present disclosure, may be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module may reside in any form oftangible storage medium. Some examples of storage media that may be usedinclude random access memory (RAM), read only memory (ROM), flashmemory, EPROM memory, EEPROM memory, registers, a hard disk, a removabledisk, a CD-ROM and so forth. A storage medium may be coupled to aprocessor such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. A software module may be asingle instruction, or many instructions, and may be distributed overseveral different code segments, among different programs, and acrossmultiple storage media. Thus, a computer program product may performoperations presented herein. For example, such a computer programproduct may be a computer readable tangible medium having instructionstangibly stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. The computer program product may include packaging material.Software or instructions may also be transmitted over a transmissionmedium. For example, software may be transmitted from a website, server,or other remote source using a transmission medium such as a coaxialcable, fiber optic cable, twisted pair, digital subscriber line (DSL),or wireless technology such as infrared, radio, or microwave.

Other examples and implementations are within the scope and spirit ofthe disclosure and appended claims. For example, features implementingfunctions may also be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations. Also, as used herein, including in theclaims, “or” as used in a list of items prefaced by “at least one of”indicates a disjunctive list such that, for example, a list of “at leastone of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., Aand B and C). Further, the term “exemplary” does not mean that thedescribed example is preferred or better than other examples.

Various changes, substitutions, and alterations to the techniquesdescribed herein can be made without departing from the technology ofthe teachings as defined by the appended claims. Moreover, the scope ofthe disclosure and claims is not limited to the particular aspects ofthe process, machine, manufacture, composition of matter, means,methods, and actions described above. Processes, machines, manufacture,compositions of matter, means, methods, or actions, presently existingor later to be developed, that perform substantially the same functionor achieve substantially the same result as the corresponding aspectsdescribed herein may be utilized. Accordingly, the appended claimsinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or actions.

1.-19. (canceled)
 20. A vertical pass-through system comprising: astorage library including: a first access zone comprising a firstplurality of media slot locations; and a second access zone comprising asecond plurality of media slot locations that includes a shared slot,said second access zone being distinct from, and vertically adjacent to,said first access zone; a first robotic assembly that operates to firstferry a storage medium between any of said first plurality of media slotlocations and said shared slot; and a second robotic assembly thatoperates to second ferry said storage medium between said shared slotand another of said second plurality of media slot locations.
 21. Thevertical pass-through system of claim 20, wherein said first access zonecomprises a support structure configured to support and position saidfirst robotic assembly in said first ferrying.
 22. The verticalpass-through system of claim 21, wherein said first robotic assembly isdisposed below said support structure.
 23. The vertical pass-throughsystem of claim 20, wherein said second access zone comprises a supportstructure configured to support and position said second roboticassembly in said second ferrying.
 24. The vertical pass-through systemof claim 23, wherein said second robotic assembly is disposed above saidsupport structure.
 25. The vertical pass-through system of claim 20,wherein said shared slot is selected from the group consisting of: a waystation slot and a media drive slot.
 26. The vertical pass-throughsystem of claim 25, wherein each of said first access zone and saidsecond access zone are in operative communication with said media driveslot.
 27. The vertical pass-through system of claim 20, furthercomprising: a physical boundary that segregates said first access zonefrom said second access zone, wherein said physical boundary comprises apass-through plate that defines an opening through which at least aportion of said first robotic assembly travels during said firstferrying.
 28. The vertical pass-through system of claim 20, wherein saidsecond access zone is disposed below said first access zone.
 29. Thevertical pass-through system of claim 20, wherein said first access zoneis disposed below said second access zone.
 30. The vertical pass-throughsystem of claim 20, wherein at least one of said first plurality ofmedia slot locations includes a shared slot, and wherein said secondrobotic assembly operates to third ferry said storage medium between anyof said second plurality of media slot locations and said shared slot ofsaid first access zone.
 31. The vertical pass-through system of claim20, further comprising: a drive control subsystem that is in operativecommunication with each of said first access zone and said second accesszone to: detect completion of said first ferrying; and initiate, inaccordance with said detection, said second ferrying.
 32. A method forvertical pass-through of storage media in a storage library, the methodcomprising: first ferrying, using a first robotic assembly, a storagemedium from any of a first plurality of media slot locations to a sharedslot, said first plurality of media slot locations being disposed in afirst access zone of a storage library, and said shared slot being oneof a second plurality of media slot locations disposed in a secondaccess zone of said storage library, said second access zone beingdistinct from, and vertically adjacent to, said first access zone; andsecond ferrying, using a second robotic assembly, subsequent tocompletion of said first ferrying, said storage medium from said sharedslot to another of said second plurality of media slot locations. 33.The method of claim 32, wherein said first ferrying comprises passing atleast a portion of said first robotic assembly through an openingdefined by a pass-through plate that physically segregates said firstaccess zone from said second access zone.
 34. The method of claim 32,wherein said first ferrying comprises moving at least a portion of saidfirst robotic assembly downward from said first access zone to saidsecond access zone.
 35. The method of claim 32, wherein said firstferrying comprises moving at least a portion of said first roboticassembly upward from said first access zone to said second access zone.36. The method of claim 32, wherein: said shared slot is selected fromthe group consisting of: a way station slot and a media drive slot; andsaid media drive slot is in operative communication with each of saidfirst access zone and said second access zone.
 37. A method forincreasing capacity of a storage library, the method comprising:physically coupling a second access zone with a first access zone forvertical adjacent attachment, said second access zone being distinctfrom said first access zone, wherein said first access zone comprises afirst robotic assembly and a first plurality of media slot locations,and wherein said second access zone comprises a second robotic assemblyand a second plurality of media slot locations that includes a sharedslot; and configuring said first robotic assembly and said secondrobotic assembly for coordinated ferrying of a storage medium betweenany of said first plurality of media slots and another of said secondplurality of media slots via said shared slot.
 38. The method of claim37, further comprising: establishing an operative communication linkbetween a drive control subsystem and each of said first access zone andsaid second access zone for said coordinated ferrying.
 39. The method ofclaim 37, where said coordinated ferrying comprises: first operatingsaid first robotic assembly to first ferry said storage medium betweensaid any of said first plurality of media slot locations and said sharedslot; and second operating said second robotic assembly to second ferrysaid storage medium between said shared slot and said another of saidsecond plurality of media slot locations.